In the trucking industry, it is important to accurately maintain time for the benefit of both the driver and for service technicians. Since a truck driver frequently travels across time zones, it is helpful to provide a clock in the cabin that is easy to change with the change in time zones. In view of this fact, it is quite common for trucks to have clocks in the cabin that display time and can be reset to the local time. Aside from the convenience to the driver, it is also useful to have a clock for keeping track of vehicle operating and diagnostic data. For example, if a problem occurs in the transmission, it is useful to know precisely when the problem occurred. Many of the sophisticated electronic controls in trucks do have a mechanism for keeping track of time. Despite the presence of these electronics on board the truck, the frequent changes in local time and/or the lack of a consistency among time keepers in the vehicle often leads to confusion in identifying when problems on the truck actually occurred.
This confusion arises, for example, when a driver tells the service technician that a problem occurred at one time and the problem actually occurred at another time. This can result when an electronic subsystem in a truck records a fault using a time clock that is not consistent with the driver's time or time used by other subsystems in the vehicle.
It is equally confusing when a fault in a subsystem is recorded at one time in a first time zone and then is recorded again at the same time in a second time zone. Consider for example, a truck travelling west from South Bend, Ind. to Chicago, Ill. If faults are recorded in terms of local time, either by the driver or the truck's electronics, it is possible to record a fault at 2:00 P.M. in South Bend and a second fault at 2:00 P.M. in Chicago. The resulting data erroneously shows that the fault occurred twice at the same time, when in reality, they occurred one hour apart.
The problems outlined above occur because of the lack of effective means for displaying and keeping track of time in the truck. The difficulty in diagnosing problems in the vehicle are further frustrated by the lack of effective systems for tracking and recording faults detected in the truck. In general, there is a need for an effective system for tracking and recording events on a consistent basis and most preferably across all subsystems installed in a truck.